The goals of this pilot proposal (PA-01-127, Pilot and Feasibility Program related to the Kidney) are to explore the ability of the different serotypes of recombinant adeno-associated viral (rAAV) vectors to enhance the efficacy of gene delivery to the kidney, particularly the intra-renal vasculature. While kidney transplantation remains the treatment of choice for end stage renal disease, chronic vascular injury secondary to transplant rejection, cyclosporine toxicity, hypertension and recurrence of disease all contribute to graft loss, necessitating return to dialysis or re-transplantation. Specific approaches that target "protective" genes into the kidney and more importantly the intra-renal vasculature would be highly beneficial in prolonging graft survival. However, most of the previous studies in this area of investigation have demonstrated limited success due to the transient nature of transgene expression and the development of adverse host immune responses. The hypothesis of this application is that the efficacy of gene delivery to the vasculature and the kidney is enhanced by the use of recombinant adeno-associated viral (rAA V) serotype 1 and 5 vectors. This hypothesis will be tested by (1) exploring the efficacy of gene delivery to the vasculature and the kidney using rAAV serotype 1 and 5 vectors in comparison to rAAV type 2, the prototypic serotype used in most gene therapy studies to date, and (2) evaluating the role of a protective gene (heme oxygenase-1, HO-1) in chronic transplant rejection using the ideal rAAV serotype. In preliminary studies, we have observed that in comparison to rAAV2, rAAV1 and rAAV5 demonstrate markedly higher transduction efficiencies at lower levels of multiplicity of infection in human vascular endothelial and smooth muscle cells. Initial studies will be performed using reporter genes, followed by transduction using rAAV vectors containing a protective gene, HO-1. The effects of rAAV-mediated HO-1 gene delivery will be evaluated in a rat aortic allograft model of chronic vascular rejection, followed by studies in a rat model of renal transplantation. These studies have important therapeutic implications in limiting vascular injury that occurs not only in renal transplantation but also in native kidney diseases secondary to diabetes and other renal diseases.